I think disability payments will qualify toward a retirement visa, but I’m not sure if they count for a DTV based on “remote work.” But, since you’ve already got enough funds in the bank, and you’re planning on actually retiring to Thailand over the long term, it sounds like the soft power DTV that language schools have started to offer might be a really nice fit — previously, the language schools had just been offering courses eligible for one year education visas, but some schools have started packaging their language classes with cultural programs that apparently qualify for the DTV.
Pro Language School seems to be offering this in Bangkok, Chiang Mai, and Pattaya — check out
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— and I’d be really curious to know if it’s possible to structure the program so you could spend a few months in Chiang Mai and a few months (like burning season) in Bangkok.
If you’re staying exclusively in Chiang Mai, TSL might also be a great option:
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Either way, if you’re planning to retire here, having a few months of language classes and some cultural immersion and a bunch of local social connections through the program might be really nice. Alternatively, if you plan on moving into one of the condos where some of the snarkier commenters live, maybe apply for a Muay Thai DTV instead. ;)